Hello and welcome epidemiology. In this lecture we're going to learn a little bit about critical thinking and evidence-based medicine. And I want to start off by telling you about my first consulting opportunity when I was a graduate student learning epidemiology. I was assisting some scientists, we were trying to determine if gynecological practice was largely evidence-based. And to do this we looked through the literature and attempted to tell if the things a gynecologist were doing commonly with pregnant women, like shaving their pubic hair and giving them enemas before birth, was worthwhile. We determined it was not worthwhile, so much of these practices weren't evidence-based, the problem though, is that we couldn't convince the gynecologist to stop doing these practices, so lesson there is, even though things may or may not be evidence-based, clinical practice is still based upon values and experiences. Having said that, today you're going to learn about how to apply epidemiological principles to help you make evidence-based medical decisions. So we're going to learn how to apply the steps of EBM, which is evidence-based medicine, we're going to learn how to rank the different kinds of study designs that you're going to discover in the process of doing your EBM searches and you're going to learn how to phrase a research question using a method that we call PICO. To begin with, I want to show you this image. This is an image that I saw on the subways of Toronto many years ago, essentially it says, a couple of things. It has two bits of information, the first is, that at approximately 3 to 5 children in every Canadian classroom have witnessed their mother being assaulted, a dire statistic, a little depressing. In the second is that 70% of men in court...